小明同学在学习酸的性质时，他进行了如下的实验探究，结果如下：
| 组别 | 相同的铝片 | 氢离子浓度相同的酸溶液 | 反应现象 | 反应片刻后添加某种试剂少量 | 反应现象 |
| 1 | 1g铝片 | 5mL稀硫酸溶液 | 气泡产生速度适中 | NaCl | 明显加快 |
| 2 | 1g铝片 | 5mL盐酸溶液 | 气泡产生较快 | Na2SO4 | 无明显变化 |
通过比较可以知道，质量相等的铝片与相同氢离子浓度的盐酸反应速率比硫酸快，同时可以看出盐酸的反应速率比硫酸的反应速率快，当向硫酸中加入氯化钠后，可以看出硫酸与铝的反应速率明显加快，可以得出氯离子对该反应的速率有影响，
答：质量相等的铝片与相同氢离子浓度的盐酸反应速率比硫酸快；Na+、SO42-对反应速率无影响；Cl-对反应速率有促进作用．
Passage Two
| During the last thirty years, the international economy has experienced a basic change. Improvements in the Internet and other communications have had important effects on world markets. Faster methods of transport from one place to another have made the world seem smaller to the businessmen. As a result, the world no longer. consists of a number of separate economies under the control of different nations. Instead, the nations have been integrated into a single economy, and the integration is becoming more and more complete every year. For the first time in history, we can truly speak of a global economy. The most dramatic example of this integration was the oil crisis of 1973 and 1974. It came as a great surprise to the public in the industrial nations to discover that they depended so heavily on imported oil. However, the best evidence for the growing integration is the rapid expansion in the volume of world trade. It went up by about 7% a year during the decade from 1990 to 2000, and in several quasi-industrial (半工业的) countries the growth was even more rapid. As a result, some imported products have become as common as domestic commodity. Some of them are too common for the public to any more realize they are foreign. Production has also become international, which is manifested by the large corporations stepping across national borders and established branches and subsidiaries in several different countries. As an example, U.S. companies are building automobiles in Canada, Germany, Britain and Japan. In some cases, components of an automobile are produced abroad and shipped to the United States, where it is then finished with the imported parts. When even the United States has the largest number of such corporations, it is not the only. Other multinationals, for instance, are based in Japan, France, Germany, the UK and Italy. Labor, too, is much more mobile than in the past. Both skilled and unskilled workers can now readily migrate from one country to another. In Europe, for example, there are large numbers of Turkish workers employed in the Germany Economy. Doctors, lawyers, and other professionals are also finding it easier to work in foreign countries. The labor market has become international, and the number of expatriate workers is continuing to grow. |
The passage is mainly about ______ .
A．the dependence of the industrial countries on imported oil
B．the fundamental change in world economy
C．the expansion of international corporations
D．the Internet and world economy